Microstructural changes and corrosion resistance of AISI 310S steel exposed to 600–800 °C

The microstructural changes in an AISI 310S stainless steel exposed to temperatures in the 600–800 °C range up to 210 h were investigated. Intense carbide precipitation occurs in all conditions. Sigma phase precipitation nucleates at the grain boundaries and becomes more intense with the increase of time and temperature. Intergranular corrosion resistance was evaluated by double loop electrochemical potentiodynamic reactivation tests. Sigma phase and chromium carbides cause severe sensitization, but healing is observed in specimens aged at 650 °C, 700 °C, 750 °C and 800 °C. Time to healing decreases with the increase of aging temperature. Anodic polarization tests were conducted in specimens aged for 210 h. Pitting potentials are found to decrease in all temperature tested.